I have an SU16FX and an SU16F. I like them both. They're lightweight, fun to shoot and hassle free to own. If AR's weren't restricted I probably wouldn't own them, but I also don't have a unicorn.
The SU16FX package is eye candy heavy. The bag it came with is strong enough, no issues with zippers etc and it includes 5 or 6 pockets for magazine storage, which is nice.
The rifle itself feels a lot more solid than the SU16F model. The weight is good, and the fore end is really solid. The buffer tube on mine is fine, but I find the extension release a little finicky. It has to be squeezed just right to position the butt stock.
The sight that comes with the rifle looks good, but that's about it. The sight picture is dark, the reticle washes out in bright light, the battery enclosure handle works itself open while shooting (and the batteries fall out!)
The accuracy of the rifle is about what I expect 3 or 4 MOA, my skills aren't wonderful so maybe it could do better. I can't find a usable bolt hold-open, although it does hold open when the magazine is empty.
That all seems a little bad, but I do like the rifle. It always makes me grin when I pull it out. LAR magazines and Beowolf magazines work well. It fires all the time, I've had no feeding or FTF issues; accuracy is good enough. The barrel does get pretty hot with mag dumps, probably normal.
The bonus of this firearm is that it is NR and light enough to carry in the woods with little effort (the SU16F model even more so.) I can strap it onto the side of my backpack and take it with me no worries.
I like mine and enjoy shooting both models.
Hope this helps.